Methods and apparatus for recording well logging measurements

ABSTRACT

According to one embodiment, distinctive indicia having a &#39;&#39;&#39;&#39;three-dimensional&#39;&#39;&#39;&#39; appearance and representative of well logging data is produced by a CRT (Cathode-ray tube) recorder by modulating both the intensity and position of the sweeping electron beam in response to variations in the data. In another embodiment, distinctive indicia in the form of a vector or arrow representative of the data is produced by sweeping the CRT electron beam in such a way that it defines an increasing spiral pattern. The electron beam is then turned on for a short pulse at the same angular position of each cycle of the spiral. For purposes of synchronization, in each of the above embodiments the beam sweep is initiated by a recurring event, such as a pulse indicative of a given incremental change in the depth level from which the data was derived. In still another embodiment, one of the above techniques is combined with presently available techniques to produce a combination log having the distinctive indicia recorded on one portion of the CRT screen and regular traces recorded on another portion of the same screen. Yet in another embodiment, alternating sweeps of the CRT electron beam are switched between two recording areas or strips on the CRT screen. A different recording medium is located adjacent each of the two recording strips thereby allowing the generation of two separate recordings. The data recorded on each medium may be completely different, or the data may be the same but recorded with different scale factors.

United States Patent [1 1 Elliott 1 Oct. 28, 1975 METHODS AND APPARATUS FOR RECORDING WELL LOGGING MEASUREMENTS [75] Inventor: Jennings W. Elliott, Friendswood,

Tex.

[73] Assignee: Schlumberger Technology Corporation, New York, N.Y.

[22] Filed: July 12, 1973 [21] Appl. No.: 378,754

[52] US. Cl 340/15;5 DS; 315/386; 3l5/392; 340/15.5 BH; 340/18 DC; 346/33 WL;

[51] Int. Cl. G01V I/40; HOlJ 29/52 [58] Field of Search..-.. ,340/l8 R, 18 DC, 15.5 DS, 340/l5.5 BH, 324 AD; 346/33 WL, 110 R; 315/22, 30, 383, 384, 385, 386, 392; 343/5 Primary Examiner-Maynard R. Wilbur Assistant Examiner-4i. A. Birmiel [5 7 ABSTRACT According to one embodiment, distinctive indicia having a three-dimensional appearance and representative of well logging data is produced by a CRT (Cathode-ray tube) recorder by modulating both the intensity and position of the sweeping electron beam in response to variations in the data. In another embodiment, distinctive indicia in the form of a vector or arrow representative of the: data is produced by sweeping the CRT electron beam in such a way that it defines an increasing spiral pattern. The electron beam is then turned on for a short pulse at the same angular position of each cycle of the spiral. For purposes of synchronization, in each of the above embodiments the beam sweep is initiated by a recurring event, such as a pulse indicative of a given incremental change in the depth level from which the data was derived. In still another embodiment, one of the above techniques is combined with presently available techniques to produce a combination log having the distinctive indicia recorded on one portion of the CRT screen and regular traces recorded on another portion of the same screen. Yet in another embodiment, alternating sweeps of the CRT electron beam are switched between two recording areas or strips on the CRT screen. A different recording medium is located adjacent each of the two recording strips thereby allowing the generation of two separate recordings. The data recorded on each medium may be completely different, or the data may be the same but recorded with different scale factors.

13 Claims, 57 Drawing Figures IG/TAL 10 4mm CONVERTER 2!] SET FLIP-FLOP :5 0 0' U.S. Patent ct. 1975 5116651 of 13 FIG. I VELOCITY ANO -58 TRAvEL TIME MEASUREMENTS 59 SIGNAL PROCESSING gg jg c/RcU/TS 68 BIAS 84A cONTROL DELAY T RESET O 76 FLIP-FLOP 82 I DEPTH SET 0 PULSE 77 GENERATOR a;

VERTICAL OR/vE c/RcU/T m g A S 53 55 F *7 4 I TRANS- T I M/TTER PULSE GEN T 50 /}4A$/7\/EGR I HORIZONTAL DRIVE 5E7 c/RcU/T 54 I FLIP FLOP J SET 69 66 0 Q S J DIGITAL 85 T0 ANALOG cONvERTER CLOCK 05- 70 cOOER v A as v R US. Patent Oct.28, 1975 Sheet2of13 3,916,372

FIG.2

FIG.3B

FIG. 3C J L r- TIME AXIS (CRT SCREEN WIDTH) l FIG. 30 I/ 0 VOLTS (0 SWEEP P05.)

90 FIG. 3E f/as W AZ/MUTH PULSE F1 I l DETEcToR FIG. 5A I l DELAYED PULSE FROM ONE SHOT F G. 5 5

ON-T/ME OFAND GATE I 110 FIG. 5 C

OUTPUT FROM D/A CONVERTER FIG. 50

U.S. Patent Oct. 28, 1975 Sh eet3of 13 3,916,372

FIG. 4

PULSE /96 ONE OETECTOR DELA Y SHOT l 97 109 I08 g;. COMBINING BIAS SING CIRCUIT CONTROL RESET COUNTER I 110 CLOCK 121 5 T 1 DEPTH MULT/PLY 5 R n PULSE OIvIOE I FUEL-LOP 4 7 OENERATOR NETWORK I 427A:

779 120 VERTICAL I DRIVE I 5 R I n INTENSITY CONTROL HORIZONTAL ORIvE CIRCUIT DIGITAL ,112 TOANALOO J CONVERTER T ONE SHOT TOA , FIG.

IHIIIHIIIIIIIIHIII IOJ US. Patent Oct. 28, 1975 Sheet7of13 3,916,372

FIG.

77A [1 FL I78 I LI J 11c FL n 770 LIIIIIIIIIIIIIIIIIlllllllll Jllllllll NE |||||I ||||IllllllllllllllllllllllllIIIIIIIIIIIIIIIILJiIlIllllllllllll ;n/-. IIIIIIIII IIIIIIIIIIIIIIIIIIIII,

I l I I I I l 776 I i l I NH 'rL i I III n! i NJ IFL I I UK I II I l 77L n I l/\/-' US. Patent Oct. 28, 1975 Sheet8of13 3,916,372

FIG. 13

US. Patent Oct. 28, 1975 Sheet110f13 3,916,372

FIG. 26A

FIG. 26B

2 DEPTH Ll/(i/ES O FIG. 28

U.S. Patent Oct.28,1975 Sheet 12 of 13 3,916,372

I I I I I I I Fl G. 23

FIG. 22

FIG 25 I I I I II METHODS AND APPARATUS FOR RECORDING WELL LOGGING MEASUREMENTS BACKGROUND OF THE INVENTION In producing well logging measurements for purposes of recording, a logging tool containing one or more exploring devices is lowered into a wellbore drilled into the earth for measuring various properties of the subsurface earth formations adjacent the wellbore. Such measurements are of considerable value in determining the presence and depth of hydrocarbon bearing zones that may exist in the subsurface earth formations. There are presently in use a variety of galvanometer recorders capable of providing satisfactory well logs or recordings representative of most types of data derived from a wellbore. Some of these galvanometer recorders are specifically useful for recording a large number of different well logging data signals at one time. Examples of such recorders are described in: (l) U.S. Pat. No. 3,449,755 which issued to G. L. Samodai et al. on June 10, 1969; (2) U.S. Pat. No. 3,488,661 which issued to D. R. Tanguy on Jan. 6, 1970; and (3) U.S. Pat. No. 3,634,865 which issued to C. O. Schafer on Jan. 11, 1972. In addition, a particularly suitable CRT recorder for recording a multiplicity of well logging measurements is described in copending application Ser. No. 15,790 filed by J. W. Elliott on Mar. 2, 1970. However, not withstanding the versatility of the recorders described in the above-mentioned patents, there are certain types of well logging data which are most advantageously displayed on a log or recording in a manner which requires even more specific methods and apparatus for generating the desired display. To date, there have been many attempts to provide the necessary recording methods and apparatus to generate these unique displays.

For example, special purpose recorders have been developed for providing sonic or acoustic logs in special forms which present some unusual recording problems. A typical sonic or acoustic logging tool provides a transmitting transducer for repetitively transmitting an acoustic burst of energy into the earth formations adjoining a wellbore in response to a recurrent firing pulse. A receiving transducer then converts the received acoustical energy into electrical signals for transmission to the surface of the earth for recording. In certain types of such sonic logging systems only the travel time At of the sonic energy in the formation is recorded. However, it has been recognized that valuable additional information about the earth formation may be obtained by recording and analysing the complete waveform. Therefore, it is of increasing importance that all subsequent arriving waves as well as the recurrent firing pulse or a pulse correlated with the recurrent firing pulse be recorded along with the first arriving wave or impulse. i

One technique for recording the waveforms comprising such acoustic or sonic logging signals'is shown in U.S. Pat. No. 3,488,658 granted to Dennis R. Tanguy on Jan. 6, 1970, wherein a glow modulator tube is utilized in conjunction with a rotating mirrorto sweep an intensity modulated light beam across a recording medium. The light beam is swept at the repetition rate of the recurrent firing pulse used to drive the transmitting transducer.

Another logging apparatus used in acoustic logging is described in U.S. Pat. No. 3,302,165 granted to T. O.

Anderson et al. on Jan. 31, 1967. The Anderson patent describes a method for obtaining so-called variabledensity logs" by utilizing an oscilloscope-camera combination. The intensity of the oscilloscope beam is varied in accordance with variations in the amplitude of the received well logging signal as the beam sweeps across the cathode-ray tube screen. Each successive sweep of the beam is representative of a different level in the wellbore.

In similar apparatus described in the U.S. Pat. No. 3,402,388 granted to Robert L. Tucker on Sept. 17, 1968, the beam intensity, during a predetermined num ber of successive sweeps, is modulated as in the Anderson patent. However, during the sweep following this predetermined number of intensity-modulated, successive sweeps, the vertical position of the beam is modulated instead of the beam intensity. After completing the sweep wherein the vertical position is modulated, the beam is again intensity-modulated for the predetermined number of sweeps. The Tucker technique results in a variable density log being produced similar to that produced by the Anderson apparatus, but which also includes a signature (the vertical position modulated trace) at spaced intervals along the log.

In another example, so-called televiewer logging apparatus (such as described in U.S. Pat. No. 3,502,169 granted to J. E. Chapman on Mar. 24, 1970 and copending application Ser. No. 827,799 also filed by J. E. Chapman on May 26, 1969) generates and displays data in such a manner that a picture of the wellbore wall is provided. This televiewer apparatus rotates a directional sonic transducer so as to continuously scan the circumference of a wellbore wall by alternately transmitting and receiving successive bursts of acoustic energy to provide the composite picture of the wellbore wall. To provide a directional reference, recurrent azimuthal signals are also transmitted to the surface of the earth as they occur, so that the resulting recorded log can be referenced to the azimuthal direction. The surface recording apparatus displays this information in a manner similar to that for displaying the sonic or acoustic logs.

Heretofore, therefore, the logs provided by the recording apparatus representative of various types of received sonic signals have been limited to sonic'At,

waveform reproduction and variations of variable density desplays. Such logs have not been completely satisfactory as such logs are often very difficult to interpret.

Therefore, to provide well logs which lend themselves to easy interpretation, it is an object of this invention to provide new and unique methods and apparatus for providing acoustic and televiewer logs having an easily interpretable three-dimensional visual appearance which is pleasant to the eye.

Still another example of data which requires unusual methods and apparatus for the most advantageous display is that used for providing; arrow-plots or vectors. Arrow-plot logs are presently used to provide information concerning: (1) the magnitude and direction of the within a predetermined land area measured at the surface. It is also of great practical importance to have information concerning the position of subsurface earth formations in areas possibly containing or known to contain oil and gas bearing formations. This information is useful in that, among other things, it may aid in locating sizeable deposits of oil and gas trapped by faults or subsurface layers of slipped strata. It is also desirable since knowledge of subsurface faults or slipped strata may allow the oil field to be developed most efficiently. For example, the simple placement of wells can radically effect both the maximum rate of production and the ultimate recovery from a single oil reservoir.

Arrow-plot logs providing such information concerning the inclination of wellbores or formations have typically been provided manually from tabulated data. Although, in some instances the arrow-plots have been produced automatically by an X Y plotter or a special purpose recorder. However, such methods have typically been time consuming and costly.

Therefore, it is another object of this invention to provide new and unique methods and apparatus for generating logs comprised of arrows or vectors representative of data corresponding to the magnitude and direction of the inclination of a wellbore or the magnitude and direction of the inclination of earth formations adjacent a wellbore.

With present logging techniques, it is likely that data from a multiplicity of downhole investigating devices of different types derived from one logging apparatus during one run or from multiple logging tools run at separate'times might be combined for recording. In such cases, it may be desirable to present all of the different logs resulting from these various investigating devices on the same recording medium. However, if the combination of logs to be presented on one recording medium includes at least one of the so-called standard or amplitude versus depth logs such as sonic-At or the like along with one of the unusual logs such as those produced by the methods and apparatus of this invention, some difficult problems arise. For example, if a CRT recorder is to be used it may be highly desirable that different sweep rates be used for the standard and unusual logs. In addition, if a single sweep of the CRT electron beam is used to produce both a standard and an unusual log such as a realtime recording of a sonic waveform, the recorder must be able to record the standard log without missing any traces and yet be ready to record the unsynchronized realtime waveform whenever it occurs. It is necessary, of course, to record the waveform whenever it occurs, unless extensive memory is provided, as the waveform will be lost and cannot be recovered. Therefore, it is a still further object of this invention to provide new and novel methods and apparatus for generating standard logs in combination with one or more of the unusual logs such as sonic should be recorded at the same time, the amount of recording medium space available for each log or curve will be severely limited. Such space limitations normally adversely affect the ease of interpretation of a log and often also affect the resolution of the many curves on the log. For example, most of the unusual logs will require a large portion of a single recording medium (typically, half). Now, if there is also a large number of standard logs to be recorded, only the unused half of the recording medium is available for this large number of standard logs. This means that each of these standard logs may either be confined to a very small track on the single recording medium which will severely limit the resolution of the logs, or the logs will have a mid-point in a particular track and be allowed wide excursions into and across other tracks. Repeated, multiple and far-reaching excursions of logs into other tracks is often very confusing and makes the task of interpreting the data very difficult. Therefore, to provide excellent resolution of all the data needed to be recorded and at the same time still provide necessary side-byside combination logs of that data where such side-byside curves are preferred, it is desirable that more space on a recording medium be available for each of the logs or curves. Even when there is not a large number of different data to be recorded at the same time, it is not unusual that a particular log or portion of a log be of greater interest than the rest. If such interest is present, it might be advantageous that the log be recorded with an expanded depth scale, or that the data be allowed to range over a large portion of the available width of the recording medium to thereby provide greater resolution and ease of interpretation.

Therefore, to provide a greater area of recording medium available for each track or log to be recorded, one embodiment of the present invention includes at least two recording mediums operably arranged with a single CRT such that each recording medium records available data at substantially the same time.

SUMMARY OF THE INVENTION The system of the present invention provides apparatus for recording various types of well logging data and comprises means for providing an energy beam which is directed by a first and second deflection means and beam intensity control means to selected locations on a recording means or surface sensitive to the energy beam. Typically, a CRT (cathode-ray tube) is used wherein the electron beam and screen of the CRT comprises the energy beam and recording means respectively. Means are also provided for generating a recurring or synchronizing signal or pulse representative of a recurring event such as the firing of a downhole acoustic transmitter, rotating a downhole device past magnetic North or transversing a particular depth interval with a downhole device. These recurring pulses which may be asynchronous (non-periodic) are used to initiate means coupled to one of the deflection means for sweeping the energy beam along one axis of the recording means. A downhole investigating device, a magnetic tape recorder or other means are provided for generating data or signals representative of the information to be recorded. These data signal are coupled to one or both deflection means and to the intensity control means and are used to modulate the intensity of the energy beam and simultaneously modulate the position of the energy beam along one or both axis of the recording means. If a temporary recording is sufficient, every trace or indicia produced on the recording medium by the sweeping energy beam is shifted or incremented in a direction perpendicular to the energy beam sweep thereby generating on the recording means (such as, for example, the screen of a CRT having a storage type screen) a composite of many traces in a stacked relationship. However, if a permanent recording is desired, the energy beam is not shifted after each sweep, but instead, a recording medium such as a photographic film located adjacent to the CRT screen is incrementally moved past the CRT screen in a direction perpendicular to the beam sweep such that each trace is recorded on the photographic film at spaced intervals in a stacked relationship.

In one embodiment of the recording apparatus discussed above, the data to be-recorded are sonic waveforms received from the subsurface formations after a burst of sonic energy has been transmitted into the formations. The recording apparatus for this embodiment also includes means for interrupting the sweep of the energy beam and then usiiig the received waveforms to modulate both the intensity and the vertical position of the energy beam simultaneously as the beam continues its sweep across the CRT screen to produce a trace with both its intensity and vertical position modulated with respect to the received sonic waveforms. When intensity and position modulated successive traces are produced on a recording means in a stacked relationship, a three-dimensional appearing log results.

In a second embodiment, data may be recorded as an arrow or vector by recording apparatus similar to that discussed above but which further includes new and improved circuitry which operates to interrupt or stop the sweeping energy beam at a selected position on the recording medium in response to one aspect of the data. This new circuitry also includes means for generating first and second sinusoidal signals each having an increasing amplitude. These two sinusoidal signals are similar in frequency and amplitude but are phase shifted from each other by 90. These two amplitude increasing sinusoidal signals are then coupled to the two deflection means to sweep the energy beam in an increasing spiral pattern. Another data signal representative of the desired orientation of the vector is coupled to the intensity control means for unblanking the energy beam at the same' angular position for each cycle of the increasing spiral pattern traveled by the beam thereby producing a series of indicia which appear as a vector.

Still in a third embodiment of the recording apparatus, the magnetic recording means or the investigating means for providing well logging data provides at least two types of data. A first control means responsive to one of the types of data is coupled to the intensity control means and deflection means and is used to modulate the intensity and position of the energy beam in a first part of the recording means as the energy beam sweeps across the recording means. The apparatus also includes means for interrupting the sweep of the energy beam at a selected location on the recording means, as well as means for switching the intensity control means and the deflection means between the first control means and a second control means which is responsive to the other type of data. The second control means is then used to modulate the intensity and position of the energy beam as the beam sweeps across the second portion of the recording medium.

The present invention also includes an embodiment which provides two recording mediums located adjacent two different areas or strips of the screen of a CRT used to provide indicia or traces. Means are included in this embodiment to shift the axis of selected energy beam sweeps such that certain sweeps produce indicia on one strip of the CRT screen and other sweeps produce indicia on the other strip of the CRT screen thereby providing two separate recordings while using only one CRT.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a typical acoustic logging tool in a wellbore along with apparatus for recording signals derived from the logging tool in accordance with one embodiment of the present invention;

FIG. 2 schematically illustrates a typical single trace representative of a well logging signal having both intensity and position modulation as may be produced by the apparatus of FIG. 1;

FIGS. 3A 3E graphically represent operation of the recording apparatus of FIG. 1:;

FIG. 4 shows a typical wellbore televiewer tool along with apparatus for recording signals derived from the televiewer tool in accordance with another embodiment of the present invention;

FIGS 5A 5D graphically represent voltage waveforms at various points in the circuitry of the apparatus of FIG. 4;

FIG. 6 shows a combination acoustic logging device and a sonic-At logging device in a single tool along with apparatus for providing recordings derived from data produced by both devices in accordance with still another embodiment of the present invention;

FIG. 7 is a circuit diagram of one of the components of FIG. 6;

FIG. 8 is representative of typical signal variations along a 6-foot interval in a typical wellbore;

FIG. 9 is representative of the recording of the signal variations of FIG. 8 provided by the apparatus of FIG.

FIGS. 10A 10] and 11A 11L graphically represent voltage waveforms at various points in the circuitry of the apparatus of FIG. 6;

FIG. 12 shows circuitry used in an alternate embodiment of FIG. 6;

FIG. 13 is illustrative of a typical three-dimensional log which may be produced by the new and improved apparatus of FIG. 6;

FIG. 14 shows apparatus for recording vectors or arrows in accordance with yet another embodiment of the present invention;

FIGS. 15 21 graphically represent voltage waveforms at various points of the circuitry of FIG. 14;

FIG. 22 graphically represents the generation of a lissajous pattern on a CRT;

FIG. 23 graphically represents the generation of a spiral pattern on a CRT;

FIG. 24 illustrates a compass-rose divided into 24 segments of 15 each;

FIG. 25 represents a vector generated by the circuitry of FIG. 14;

FIGS. 26a-b represent the voltage waveforms applied to the horizontal and vertical drive circuits of a CRT to generate the vector of FIG. 25;

FIG. 27 shows apparatus for providing typical recordings in combination with recorded vectors accord- {ing to another embodiment of the present invention; Q FIG. 28 illustrates scale lines on a recording as generated by the apparatus of FIG. 27;

FIG. 29 shows segments of the scale lines illustrated in FIG. 28 produced during one sweep of the CRT electron beam of the apparatus of FIG. 27.

DETAILED DESCRIPTION OF THE INVENTION Now referring to FIG. 1, there is shown apparatus for producing and recording well logging signals in such a manner so as to provide a log having a threedimensional effect in accordance with one aspect of this invention. A typical downhole investigating tool 50 for investigating earth formations traversed by a wellbore 51 is supported in the wellbore by a typical multiconductor logging cable 52 which is raised and lowered by a typical winch (not shown).

The tool 50 in the present embodiment is illustrated as a typical sonic logging tool having at least one transmitter T for periodically emitting bursts of acoustic energy and one or more receivers, as at R, spaced at suitable intervals from the transmitter for receiving the acoustic energy reflected from the earth formations. Firing pulse timing circuitry 53 for providing a firing pulse to the transmitter T within tool 50 comprises a master timing oscillator 54 having a substantially constant frequency which provides timing signals to transmitter pulse generator 55. generator 55 in turn supplies the firing pulses to transmitter T. This pulse timing circuitry 53 is in reality contained within tool 50 but is shown outside thereof for purposes of clarity. It should be noted that even though master timing oscillator 54 and transmitter pulse generator 55 are illustrated as part of the downhole well tool 50, it is often desirable that these items be located within the surface apparatus. A detailed explanation of suitable downhole circuitry for providing firing pulses to the transmitter T and synchronized timing pulses T to the earths surface may be found in U.S. Pat. No. 3,590,940 granted to G. L. Legar on July 6, 1971. The signals received by receiver R as well as timing signals T which are comelated with the firing of transmitter T are returned to the surface of the earth through cable 52 through utilization of suitable downhole circuitry (not shown) to suitable signal processing circuits 56. Signal processing circuits 56 are effective to extract the necessary information and process it such that it is available for recording and any other desired uses. For example, the timing pulse T is detected by circuits 56 which then generate a synchronization pulse or signal for the surface apparatus representative of the timing signal T This synchronization pulse is provided to the other surface apparatus by way of conductor 57. How this synchronization pulse is used by the apparatus of this circuit will be described in detail hereinafter. In addition, the extracted information may also be applied to velocity and travel time measurement circuits 58. Other arrangements of the tool 50 can, of course, be used with the recording methods and apparatus of the present invention. It should be understood, at this point, that although this invention is described with respect to online downhole apparatus, the information derived from the downhole apparatus could be recorded on a storage medium such as magnetic tapes, magnetic disks or the like and later played back and recorded for visual observation by the methods and apparatus of this invention.

The signals from signal processing circuits 56, representative of the received acoustic waveforms, are applied to a combining circuit 59 whose output is connected to the energy or electron beam intensity control grid 60 of a CRT (cathode-ray tube) 61. In addition to being connected to the intensity control grid 60 of CRT 61, it is of particular significance to note that in this embodiment of the invention the output of combining circuit 59 is also applied to a vertical directing or drive circuit 62 for applying a signal representative of the output of combining circuit 59 to the vertical deflection means such as the vertical deflection plates 63 of CRT 61. It should be understood, of course, that the electron beam deflection means could alsocomprise magnetic coils. In addition, as will be explained hereinafter, the electron beam 64 of CRT 61 is swept horizontally across the screen by means of horizontal deflection plates 65 connected to a horizontal directing or drive circuit 66.

To provide a proper bias level for electron beam 64 as it travels across CRT screen 67, the recording apparatus of the present invention further includes bias control circuit 68 which is arranged to normally inhibit a visible image being produced on CRT screen 67. Then, to record a trace, bias control circuit 68 cooperates to supply a bias signal of a selected magnitude to combining circuit 59. This recording bias level is desirably set so that a medium intensity trace will be produced at approximately the mid-point of screen 67 when the data signal input is zero. Therefore, if a received input signal has both positive and negative portions, the positive portions of the signal will result in a darker or more intense and positively displaced trace being recorded; and the negative portions will result in a less intense and negatively displaced trace being recorded. Bias control circuit 68 could, for example, be as switching arrangement, such as semi-conductor switches, a relay or the like which normally supplies a negative voltage to combining circuit 59 but, which when energized, supplies proper positive bias voltage to the combining circuit. To provide the horizontal sweep of the electron beam 64 across the CRT screen 67, the input voltage applied to horizontal drive circuit 66 is a saw-tooth or ramp voltage generated by a D/A (Digital to Analog) converter 69 in response to the digital output of counter 70. The pulse input to counter 70 is supplied from clock source 71 by means of AND gate 72. As will be discussed later, AND gate 72 is arranged to pass the clock pulses only in response to a signal provided by combining a synchronization pulse from the signal processing circuits 56 and a depth pulse which is representative of tool 50 moving a precise interval through wellbore 51 and which is generated from depth pulse generator 73.

Thus, in accordance with this embodiment of the present invention, as the electron beam 64 of CRT 61 is swept horizontally across the CRT screen 67 which screen is, of course, sensitive to the electron beam, a trace or indicia will be produced on CRT screen 67 which varies both in intensity and in vertical position in response to the combined signal from combining circuit 59. FIG. 2 illustrates a typical single trace produced on CRT screen 67 by the apparatus of this invention. In this illustrative example, the trace is shown having very dark or high-intensity positive peaks which intensity decreases as the vertical position of the trace representative of the signal amplitude decreases to pro duce negative peaks.

In order to produce a permanent record of the successive intensity and position modulated sweeps of the CRT beam 64 a movable recording medium 74 is provided for recording the successive transverse traces formed on CRT screen 67. In the preferred embodiment of the present invention, screen 67 of CRT 61 is provided with a strip of fiber optics 75. Such fabrication of the screen 67 allows high resolution and eliminates the need of a complicated lens system. Recording medium 74 is passed in close proximity to fiber optic strip 75 so that the traces or indicia appearing on CRT screen 67 will be successively recorded by recording medium 74. Typically, the rate of movement of recording medium 74 past fiber optic strip 75 varies with the rate of movement of tool 50 in the wellbore.

Such correlation between the rate of movement of the recording medium 74 and the rate of movement of the well tool 50 is desirable since, if the recording medium 74 were simply driven at a constant speed, a decreased travel speed of the logging tool 50 would result in an increase in the number of data traces per unit length of the recording medium; and conversely, a decreasing number of data traces per unit length would occur at faster travel speeds of tool 50. Therefore, the new and improved circuitry shown in FIG. 1 provides for a constant number of data traces per unit length of the recording medium as is also shown in the heretofore mentioned Tanguy patent (No. 3,488,661) and copending Elliott application Ser. No. 15,790. This is accomplished by recording well logging data from selected intervals of depth at uniform spacings along the length of the moving recording medium. To control the placement of the traces on recording medium 74, a typical measuring wheel 76 is operatively engaged with cable 52 for rotating shaft 77 as a function of the movement of cable 52 and, thus, the depth of the tool 50 in the wellbore 51. Shaft 77 is coupled to depth pulse generator 73 for generating pulses as given incremental lengths of cable 52 pass measuring wheel 76. The pulses from depth pulse generator 73 are then combined with the synchronizing pulses from signal processing circuits 56 by the apparatus to be discussed hereinafter in such a manner that recording medium 74 is advanced past CRT screen 67 from supply reel 78 to take-up reel 79 by means of stepping motor 80, at a rate which varies with the rate of movement of logging tool 56 through the wellbore 51.

Accordingly, it will be appreciated that the advancement of the recording medium 74 by stepping motor 80 is efl'ective for longitudinally displacing each successive trace which trace is representative of data produced from preselected depth intervals produced by the transverse sweep of beam a small and precise distance from the preceding trace. In addition, as will be discussed later, the successive traces are produced in a stacked relationship on recording medium 74 with the starting point of each trace being representative of the firing pulse and being aligned along the length of the recording medium. As previously described, each trace varies in accordance with variations in the amplitude of the data signal in both density and vertical position as it passes across the width of recording medium 74. As a result, when the successive traces are recorded according to this embodiment of the present invention, a

representation of the sonic signals is produced which has an unusual three-dimensional appearance.

Circuitry suitable for providing necessary synchronization must, of course, be provided between the horizontal sweep of the electron beam 64, the received sonic signals and depth pulses. To accomplish this, the pulses from depth pulse generator 73 set flip-flop 81 whose Q output energizes AND gate 82. The synchronizing pulse from signal processing circuits 56 is then supplied by way of AND gate 82 to the set input of flip-flop 83. The synchronizing pulse from signal processing circuits 56 which set flip-flop 83 also resets flip-flop 81 after a suitable delay by a delay circuit 84. This delay is selected so as to eliminate a race between the arrival of the pulse at the set input of flip-flop 83 and at the reset input of flip-flop 81. Thus, the delay circuit 84 insures that flip-flop 83 will be energized at the appropriate time. The Q output from flip-flop 83 energizes the bias control circuitry 68 which as was discussed heretofore, preferably serves to bias the electron beam 64 to a mid-screen position (on the vertical axis) and at a medium intensity level in preparation for each horizontal sweep of the electron beam 64 across CRT screen 67. In addition to energizing bias control circuitry 68, the output of flip-flop 83 also provides the necessary signal to enable AND gate 72 to pass the clock pulses from clock 71 to counter 70. When the necessary number of clock pulses for sweeping the electron beam 64 completely across the screen 67 have been provided from clock 71, decoder 85 will generate a pulse output signal which is applied to the reset inputs of counter and flip-flop 83 respectively. The reset signal resets the binary digitall output of counter 70 to zero and changes the Q output of flip-flop 83 from a l to a 0, so that no further clock pulses can be passed to counter 70 through AND gate 72. The reset signal from decoder is also amplified by power amplifier 86 for driving the recording medium stepping motor in the manner heretofore described. Since flipflop 81 is set only at equal depth intervals; bias control circuit 68, stepping motor 80, and horizontal drive circuitry 66 can operate only at the selected depth intervals. It can be seen, therefore, that successive traces will be recorded on recording medium 74 at equal spacings which traces are representative of data at equal intervals of depth.

Referring now to FIGS. 3A 3E, the operation of components of the apparatus shown in FIG. 1 is graphically displayed. FIG. 3A shows an example of the signals produced by the signal processing circuits 56 of FIG. 1. Portion 87 of the illustrated signal is representative of one of the timing pulses T.,, and portion 88 of the illustrated signal is representative of one of the re ceived sonic signals picked up by receiver R in tool 50. FIG. 3B is representative of the synchronization pulse provided by signal processing circuits 56 on conductor 57 in response to the timing pulse T FIG. 3C shows the output waveform of flip-flop 83 which causes the bias control circuit 68 to bias the electron beam 64 of CRT 61 to the proper voltage level for producing a trace on the CRT screen 67. The pulse shown in FIG. 3C is also, of course, representative of the time period AND gate 72 passes clock pulses to counter 70 which in turn provides a digital binary signal to D/A converter 69. Referring now to FIG. 3D, there is shown a plot of the horizontal position of the electron beam 64 as a function of time for a single sweep. FIG. 3D is also representative of the output of D/A converter 69. In addition, since the electron beam 64 moves across screen 67 of CRT 61 at a constant velocity, the time or horizontal axis of FIG. 3D can also be considered to be the width of the CRT screen 67. FIG. 3E is representative of the actual signal applied to the intensity and vertical drive circuitry of CRT 61 from combining circuit 59. Portion 89 of the signal shown in FIG. 3E depicts the rise of the signal in response to the bias voltage applied to the combining circuit 59 from bias control circuit 68 when flip-flop 83 is set. Portion 90 of the waveform shown in FIG. 3E depicts the subsequent modulation of the signal as it varies in response to the received sonic signal. It can be seen, therefore, that both the vertical position of the electron beam 64 and the intensity of electron beam 64 will vary in response to the signal as shown in FIG. 3B.

It is to be understood that the above embodiment was described with regard to the use of a recording medium moving past the CRT screen for purposes of providing a permanent record. If, however, a permanent recording is not necessary, a temporary recording may be provided by the apparatus of this invention by using a CRT having a storage screen. With such apparatus the first sweep would start, for example, at the lower left-hand corner of the screen and sweep across. Each successive sweep would be incremental toward the top of the screen a predetermined increment and would represent a new depth of the well logging tool. After the screen is filled, the screen would be erased and the process would then be repeated.

Now concerning the televiewer investigating apparatus, there is shown in FIG. 4 typical sonic downhole televiewer apparatus 91 for scanning the wall of the wellbore 92. A detailed description of downhole apparatus, as well as complex synchronization circuits found in surface apparatus suitable for use with the present invention is included in US. Pat. No. 3,502,169 and copending application, Ser. No. 827,799 both filed in the name of J. E. Chapman and heretofore mentioned. However, to aid in understanding how the present invention works in combination with such apparatus, a very brief summary of the televiewer apparatus is included herein. The downhole apparatus 91 is arranged for periodically energizing an acoustic transducer 93 which rotates around the vertical axis of the wellbore as the apparatus 91 moves through wellbore 92. The acoustical signal resulting therefrom is reflected from the wall of the wellbore back to the transducer 93 where it is detected. The detected or received signals and a pulse representative of the acoustic transducer firing is supplied to processing circuits 94 located at the surface of the earth. The downhole apparatus 91 also includes a north azimuthal detector 95 for supplying a recurring pulse to pulse detector 96 located at the surface of the earth each time rotating transducer 93 passes magnetic North.

After processing by processing circuits 94 to assure that noise is not detected as a received signal, and to modify the received signals as necessary to make them compatible with the surface equipment comprising this invention, the received signals are applied to a combining circuit 97 where a selected constant bias voltage is combined with the received signals. The output from combining circuit 97 is then supplied to an intensity control circuitry 98 and a vertical drive circuitry 99 for providing both intensity and position modulation of the CRT electron beam 100 by modulating the input signal to control grid 101 and vertical plates 102 of CRT 103.

Therefore, it will be appreciated that the sweep of the CRT electron beam 100 should be synchronized with the rotation of the downhole transducer 93. This synchronization is provided by use of the recurring azimuth pulses which are generated by the north azimuthal detector 95 each time the downhole transducer 93 is pointed toward magnetic North and are supplied to pulse detector 96. The pulse detector 96 typically includes a discriminating amplifier which is responsive to only the azimuth pulses for eliminating noise, and a suitable waveshaping circuit, such as a Schmitt trigger, for squaring up the azimuth pulses received at the surface of the earth.

Azimuth pulses from pulse detector 96 are applied to one-shot 104 which in turn provides a pulse output to stepping motor 105 by way of power amplifier 106 to incrementally move the recording medium for each successive trace. The recurring azimuth pulses representative of North are also applied to the reset input of counter 107 such that the output of the counter is reset to zero. Further description of counter 107 and its operation for providing the horizontal sweep of electron beam 100 of CRT 103 will be set out hereinafter.

For purposes of better appreciating the time relationship between the azimuth pulse and operation of the remaining circuit, refer to FIGS. 5A 5D. Azimuth pulses, as shown in FIG. 5A, are also used to trigger one-shot 108 after a suitable short delay by delay circuitry 109. The delay provided by delay circuitry 109 is to insure that counter 107 will be reset to zero prior to one-shot 108 providing an output to AND gate 110, and is preferably set for the minimum possible delay time. The delayed output pulse from one-shot 108 shown in FIG. 53 may be related to the recurring azimuth pulses by comparing FIGS. 5A and 5B. The output of one-shot 108 is applied to AND gate 110 and allows AND gate 110 to pass clock pulses from a clock source 11 l to counter 107. FIG. 5C shows the time period that gate 110 passes clock pulses to counter 107. Counter 107 then works in conjunction with D/A converter 112 and horizontal drive circuit 113 to provide horizontal drive to the CRT electron beam 100 in the same manner described above with respect to FIG. 1.

It should be noted at this point, however, that to insure a substantially complete display of the scanned wall of the wellbore 92, the time necessary for a complete sweep of electron beam 100 across the screen of CRT 103 is selected to be slightly greater than the expected time between the recurring azimuth pulses. This means, of course, that the time necessary for a complete sweep of electron beam 100 across the CRT screen is slightly greater than the expected time for the downhole transducer 93 to make a complete scan of the wall of the wellbore 92. FIG. 5D shows the analog ramp signal produced by D/A converter 112 in response to the output of counter 107. The output of D/A converter 112 is applied to horizontal drive circuit 113 which in turn furnishes the control signals applied to horizontal plates 114 of CRT 103. The dashed line attached to the ramp signal of FIG. 5D illustrates the additional signal that might be needed to provide full sweep of the beam across the screen of CRT 103. It should be recalled from the earlier discussed embodiment that the time axis of FIG. 5D may be considered to be the width of the CRT screen. 

1. Apparatus for recording well logging data comprising: means for producing synchronizing signals representative of a recurring event; means for providing an energy beam having first and second beam deflection means and beam intensity control means; recording means sensitive to said energy beam; driving means responsive to said synchronizing signals and coupled to said first deflection means adapted for repetitively sweeping said energy beam along an axis of said recording means; means for interrupting selected sweeps of said energy beam at a selected location along said axis; means for providing first and second well logging data representative of subsurface characteristics at preselected depth intervals; means coupled to said intensity control means and responsive to said first well logging data for modulating the intensity of said energy beam during sweeps of said energy beam to produce first indicia on said recording means; means coupled to said first and second beam deflection means and said intensity control means and responsive to said second well logging data for modulating the intensity and the location of said interrupted sweeps of said energy beam to produce second indicia on said recording means; and means for moving one of said recording means and said axis with respect to the other one such that indicia produced by successive sweeps of said energy beam are at spaced intervals on said recording means and are representative of well logging data at preselected depth intervals.
 2. Apparatus for recording well logging data comprising: means for producing synchronizing signals representative of a recurring event; a cathode-ray tube having first and second deflection means and an intensity control means; driving means responsive to said synchronizing signals and coupled to said first deflection means for providing a first signal to repetitively sweep the electron beam of said cathode-ray tube along an axis of the screen of said cathode-ray tube; means for interrupting selected ones of said first signals to stop selected sweeps of said electron beam at a selected location along said axis; means for providing first and second well logging data representative of subsurface characteristics at preselected depth intervals; means coupled to said intensity control means and responsive to said first well logging data for modulating the intensity of said electron beam during sweeps of said electron beam to produce first indicia on said screen; means coupled to said first and second deflection means and said intensity control means and responsive to said second well logging data for modulating the intensity and location of said electron beam while said selected sweeps of said electron beam are interrupted to produce second indicia on said screen; a recording medium located adjacent said screen of said cathode-ray tube adapted for recording indicia produced thereon; and means for moving said recording medium such that indicia produced by successive sweeps of said electron beam along a first axis of said screen are recorded at spaced intervals along said recording medium and are representative of well logging data at preselected intervals.
 3. Apparatus for recording well logging data comprising: means for producing synchronizing signals representative of a recurrent event; a cathode-ray tube having first and second deflection means and intenSity control means; directing means responsive to said synchronizing signal and coupled to said first deflection means for providing a first signal to repetitively sweep the electron beam of said cathode-ray tube along an axis of the screen of said cathode-ray tube; means for interrupting selected ones of said first signal to stop selected sweeps of said electron beam at a selected location along said axis; means for providing first and second well logging data representative of subsurface characteristics at preselected depth intervals; means coupled to said intensity control means and responsive to said first well logging data for modulating the intensity of said electron beam during sweeps of said electron beam to produce first indicia on said screen; means coupled to said first and second deflection means and said intensity control means and responsive to said second data for modulating the intensity and location of said electron beam while said selected sweeps of said signal are interrupted to produce second indicia on said screen; and means for relocating at spaced intervals the location of said axis along which successive sweeps of said electron beam move such that indicia produced by successive sweeps of said electron beam are located at spaced intervals and are representative of well logging data at preselected depth intervals.
 4. Apparatus for recording well logging data comprising: means for producing synchronizing signals representative of a recurring event; means for providing an energy beam having first and second beam deflection means and beam intensity control means; recording means sensitive to said energy beam; directing means responsive to said synchronizing signals and coupled to said first deflection means and adapted for repetitively sweeping said beam of energy along an axis of said recording medium; means for providing first and second well logging data representative of subsurface characteristics at selected depth intervals; first control means coupled to said first and second deflection means and said intensity control means and responsive to said first well logging data for modulating at least the intensity and the location around said axis of said energy beam to produce first indicia on said recording medium; second control means coupled to said first and second deflection means and said intensity control means and responsive to said second well logging data for modulating at least the intensity of said energy beam to produce second indicia on said recording means; switching means for switching said first and second deflection means and said intensity control means between one of said first and second control means to the other one at a selected location on said axis; and means for moving one of said recording means and said axis with respect to the other one such that indicia produced by successive sweeps of said energy beam are at spaced intervals on said recording means and are representative of well logging data at preselected depth intervals.
 5. Apparatus for recording well logging data comprising: means for producing synchronizing signals representative of a recurring event; a cathode-ray tube having a first and second deflection means and intensity control means; means responsive to said synchronizing signals and coupled to said first deflection means for providing a first signal to repetitively sweep the electron beam of said cathode-ray tube along an axis of the screen of said cathode-ray tube; means for providing first and second well logging data representative of subsurface characteristics from selected depth intervals; first control means coupled to said first and second deflection means and said intensity control means and responsive to said first well logging data for modulating at least the intensity and location around said axis of said electron beam to produce first indicia on said screen; second control means coupled to said first and second deflection means and said intensity control means and responsive to said second well logging data for modulating at least the intensity of said electron beam to produce second indicia on said screen; switching means for selectively switching said second deflection means and said intensity control means between said first and second control means at a selected location along said axis; a recording medium located adjacent said screen of said cathode-ray tube adapted for recording indicia produced on said screen; and means for moving said recording medium such that indicia produced by successive sweeps of said electron beam along a first axis of said screen are recorded at spaced intervals on said recording medium and are representative of well logging data at selected depth intervals.
 6. Apparatus for recording well logging data comprising: means for producing synchronizing signals representative of a recurring event; a cathode-ray tube having first and second deflection means and intensity control means; means responsive to said synchronizing signals and coupled to said first deflection means for providing a first signal to repetitively sweep the electron beam of said cathode-ray tube along an axis of the screen of said cathode-ray tube; means for providing first and second well logging data representative of subsurface characteristics at selected depth intervals; first control means coupled to said first and second deflection means and said intensity control means and responsive to said first well logging data for modulating at least the intensity and location around said axis of said electron beam to produce first indicia on said screen; second control means coupled to said first and second deflection means and said intensity control means and responsive to said second well logging data for modulating at least the intensity of said electron beam to produce second indicia on said screen; switching means for selectively switching said first and second deflection means and said intensity control means between said first and second control means at a selected location along said axis; and means for relocating at spaced intervals the location of said axis along which successive sweeps of said electron beam move such that indicia produced by successive sweeps of said electron beam are located at spaced intervals and are representative of well logging data at preselected depth intervals.
 7. A method of recording well logging data comprising the steps of: generating synchronizing signals representative of a recurring event; repetitively sweeping an energy beam along an axis of a recording means in response to said synchronizing signals said recording means being sensitive to said energy beam; modulating the intensity of said energy beam with first well logging data representative of subsurface characteristics at preselected depth intervals during sweeps of said energy beam to produce first indicia on said recording means; interrupting selected sweeps of said energy beam at a selected location along said axis; modulating the intensity and the location of said energy beam with second well logging data representative of subsurface characteristics at preselected depth intervals while said selected sweeps of said energy beam are interrupted to produce second indicia on said recording means; and moving one of said recording means and said axis with respect to the other one such that indicia produced by successive sweeps of said energy beam at spaced intervals on said recording means and are representative of well logging data at preselected depth intervals.
 8. A method of recording well logging data comprising the steps of: producing a synchronizing signal representative of a recurring event; repetitively sweeping the electron beam of a cathode-ray tube along a first axis of the screen of said cathode-ray tube in response to said synchronizing signaLs; modulating the intensity of said electron beam with first well logging data representative of subsurface characteristics at preselected depth intervals during sweeps of said electron beam to produce a first indicia on said screen; interrupting selected sweep of said electron beam at a selected location along said first axis; modulating the intensity and location of said electron beam with second well logging data representative of subsurface characteristics at preselected depth intervals while said selected sweeps of said electron beam are interrupted to produce second indicia on said screen; recording on a first recording medium located adjacent said screen of said cathode-ray tube indicia produced on said screen; and moving said first recording medium such that indicia produced by successive sweeps of said electron beam along said axis of said screen are recorded at spaced intervals along said first recording medium and are representative of well logging data at preselected depth intervals.
 9. A method of recording well logging data comprising the steps of: producing synchronizing signals representative of a recurring event; repetitively sweeping the electron beam of a cathode-ray tube along an axis of the screen of said cathode-ray tube in response to said synchronizing signals; modulating the intensity of said electron beam with well logging data representative of subsurface characteristics at preselected depth intervals during sweeps of said electron beam to produce first indicia on said screen; interrupting selected sweeps of said electron beam at a selected location along said axis; modulating the intensity and location of said electron beam with well logging data representative of subsurface characteristics at preselected depth intervals while said selected sweeps of said signal are interrupted to produce second indicia on said screen; and relocating at spaced intervals the location of said axis along which successive sweeps of said electron beam move such that indicia produced by successive sweeps of said electron beam are located at spaced intervals and are representative of well logging data at preselected depth intervals.
 10. A method of recording well logging data comprising the steps of: producing synchronizing signals representative of a recurring event; repetitively sweeping an energy beam along an axis of a recording means in response to said synchronizing signals, said recording means being sensitive to said energy beam; modulating at least the intensity and the location around said axis of said energy beam with a signal from first control means responsive to well logging data representative of subsurface characteristics at selected depth intervals to produce first indicia on said recording means; modulating at least the intensity of said energy beam with a signal from a second control means responsive to well logging data representative of subsurface characteristics at selected depth intervals to produce second indicia on said recording means; switching between said first and second control means at a selected location on said axis; and moving one of said recording means and said axis with respect to the other one such that indicia produced by successive sweeps of said energy beam are at spaced intervals on said recording means and are representative of well logging data at preselected depth intervals.
 11. A method of recording well logging data comprising the steps of: generating synchronizing signals representative of a recurring event; repetitively sweeping a beam of energy along an axis of a recording means in response to said synchronizing signals, said recording means being sensitive to said energy beam; modulating the intensity of said energy beam with first well logging data representative of subsurface characteristics at preselected depth intervals during sweeps of said energy beam to produce first indicia on said recording means; interrupting selected sweeps of said energy beam at a selected location along said axis; simultaneously modulating both the intensity and the location of said energy beam with second well logging data representative of subsurface characteristics at preselected depth intervals while said selected sweeps of energy beam are interrupted to produce second indicia on said recording means which varies both in intensity and in location with respect to said axis as a function of said second well logging data; and moving one of said recording means and said axis with respect to the other one such that indicia produced by successive sweeps of said energy beam are at spaced intervals on said recording means and are representative of well logging data at preselected depth intervals.
 12. The apparatus of claim 1 wherein said means coupled to said first and second beam deflection means and said intensity control means simultaneously modulates, in response to said second well logging data, the intensity and the location of said energy beam.
 13. The apparatus of claim 2 wherein said means coupled to said first and second deflection means and said intensity control means simultaneously modulates, in response to said second well logging data, the intensity and the location of said energy beam. 